Crystallised Control: Unlocking the Secrets to Polymorph Patents in India

Polymorphs are compounds with the same chemical composition but different crystalline structures, resulting in varied physical properties like solubility and dissolution rates. These differences make polymorphs vital in pharmaceuticals, agrochemicals, and pigments.

Securing patents for polymorphs can extend protection for a primary drug, though Indian Patent law requires significant therapeutic efficacy for such patents to be granted. Navigating polymorph patenting in India requires careful consideration of therapeutic efficacy standards and inventive merit. This article examines these requirements alongside practical insights and judicial developments.

Patentability of Polymorphs in India

To patent a polymorph in India, applicants must satisfy the criteria under Section 2(1)(j): novelty, inventive step, and industrial applicability. Under Section 10(5), they must also provide a detailed and clear description of the polymorph and the method, including the conditions under which the polymorph is obtained and any specific characteristics that distinguish it from known forms.

Section 3(d) additionally requires significantly enhanced efficacy for derivatives to avoid evergreening. It states: “the mere discovery of a new form of a known substance which does not result in the enhancement of the known efficacy of that substance or the mere discovery of any new property or new use for a known substance or of the mere use of a known process, machine or apparatus unless such known process results in a new product or employs at least one new reactant. Explanation – salts, esters, ethers, polymorphs, metabolites, pure form, particle size, isomers, mixtures of isomers, complexes, combinations, and other derivatives of known substance are considered to be the same substance unless they differ significantly in properties with regard to efficacy.”

To fulfill the requirements of Section 3(d), applicants must provide experimental data in the specification that demonstrates significantly enhanced “efficacy” of the claimed polymorph (in the case of pharmaceutics, “efficacy” will be “therapeutic efficacy” only) over the known polymorphs. Additional experimental data may be submitted later during prosecution through an affidavit, provided there is support in the originally filed specification.

Patentability of Novel Processes for Polymorphs

Processes for preparing novel polymorphs may be patentable if they result in improved properties and do not fall under Section 3(d). To overcome inventive step objections, applicants must show that the process steps or parameters are novel and not hinted at in prior art. For processes preparing known polymorphs, improvements like better yield, purity, or technical advancement must be demonstrated with comparative data.

Judicial Precedents: Key Case Summaries

In Novartis AG vs. Union of India & Ors [1], the Supreme Court clarified that the ‘efficacy’ referred to in the explanation of Section 3(d) means ‘therapeutic efficacy’. This case has set a high bar for proving enhanced efficacy in polymorphs.

In F. Hoffmann-La Roche Ltd. vs. Cipla Limited [2], the Delhi High Court reiterated the need to prove that derivatives of known substances meet the efficacy standard.

Meanwhile, in AbbVie Inc v Deputy Controller of Patents & Designs [3], the Madras High Court ruled that polymorphs not publicly known before the priority date may not qualify as a ‘known substance’ under Section 3(d). The Court acknowledged that structural differences in the chemical composition can exclude certain polymorphs from prior art, allowing them to be patented.

These precedents collectively emphasize the high standard for proving therapeutic efficacy and the interpretation of Section 3(d) in polymorph patenting.

Conclusion and Practical Takeaways for Patenting Polymorphs in India

Patenting polymorphs and their preparation methods in India requires a higher standard of inventiveness. To maximize success:

• Provide detailed descriptions of the polymorph’s physical and chemical parameters to avoid added subject matter objections during prosecution.
• Demonstrate significantly enhanced efficacy, especially therapeutic efficacy for pharmaceuticals, with robust experimental data.
• Emphasize novelty and technical advancements, such as improved yield, purity, or unexpected effects, distinguishing the polymorph from amorphous or other crystalline forms in prior art.

References

[1] 13 S.C.R. 148

[2] CS (OS) No.89/2008 and C.C. 52/2008

[3] (T) CMA (PT) No. 150 of 2023